Installation process hangs with PHP 7.1
This behavior is kind of strange. During the installation process of TYPO3 CMS 8.5-dev (25d53cc07f991fbfed3ad96c86de5af52457af0a) the execution hangs if the doctrine Lexer instance is created. It seems to be a PHP 7.1 issue that could be reproduced with 7.1-RC5 and 7.1.0 on Mac OS.
Besides that, I've created a new PHP bug report: https://bugs.php.net/bug.php?id=73789